#include <stdio.h>
#include <math.h> 
int main()
{
	//freopen("zz_test\\test5.in", "r", stdin);
	//freopen("zz_test\\test5.out", "w", stdout);
	
	double s = 0, k = 0, a = 0;
	scanf("%lf %lf %lf", &s, &k, &a);
	double t = s / ( a + k) + s / (a-k);
	printf("%.2lf", t);
	return 0;
} 
